This invention relates to a ring binder mechanism for retaining loose-leaf pages, and in particular to an improved ring binder mechanism for opening and closing ring members and for locking closed ring members together.
A ring binder mechanism retains loose-leaf pages, such as hole-punched pages, in a file or notebook. It has ring members for retaining the pages. The ring members may be selectively opened to add or remove pages or closed to retain pages while allowing the pages to be moved along the ring members. The ring members mount on two adjacent hinge plates that join together about a pivot axis. An elongate housing loosely supports the hinge plates within the housing and holds the hinge plates together so they may pivot relative to the housing.
The undeformed housing is slightly narrower than the joined hinge plates when the hinge plates are in a coplanar position (180E). So as the hinge plates pivot through this position, they deform the resilient housing and cause a spring force in the housing that urges the hinge plates to pivot away from the coplanar position, either opening or closing the ring members. Thus, when the ring members are closed the spring force resists hinge plate movement and clamps the ring members together. Similarly, when the ring members are open, the spring force holds them apart. An operator may typically overcome this force by manually pulling the ring members apart or pushing them together. Levers may also be provided on one or both ends of the housing for moving the ring members between the open and closed positions. But a drawback to these known ring binder mechanisms is that when the ring members are closed, they do not positively lock together. So if the mechanism is accidentally dropped, the ring members may unintentionally open.
Some ring binder mechanisms have been modified to include locking structure to block the hinge plates from pivoting when the ring members are closed. The blocking structure positively locks the closed ring members together, preventing them from unintentionally opening if the ring mechanism is accidentally dropped. The blocking structure also allows the housing spring force to be reduced because the strong spring force is not required to clamp the closed ring members together. Thus, less operator force is required to open and close the ring members of these mechanisms than in traditional ring mechanisms.
Some of these ring mechanisms incorporate the locking structure onto a control slide connected to the lever. The lever moves the control slide (and its locking structure) to either block the pivoting movement of the hinge plates or allow it. But a drawback to these mechanisms is that an operator must positively move the lever after closing the ring members to position the locking structure to block the hinge plates and lock the ring members closed. Failure to do this could allow the hinge plates to inadvertently pivot and open the ring members, especially if the mechanisms are accidentally dropped.
Some locking ring binder mechanisms use springs to move the locking structure into position blocking the hinge plates when the ring members close. Examples are shown in co-owned U.S. patent application Ser. Nos. 10/870,801 (Cheng et al.), 10/905,606 (Cheng), and 11/027,550 (Cheng). These mechanisms employ separate springs to help lock the mechanisms.
Accordingly, there is a need for a simple ring binder mechanism that readily locks ring members together when the mechanism is closed without requiring additional spring components to do so.